Welcome to model rocketry and to the forum.
My favorite line from movie Sully
“Can we get serious now?”
Your idea sounds cool, but you are running into problems immediately because apparently you don’t seem to have any significant Rocketry experience flying proven simple single engine manufacturer designed single motor kits and you want to START with a scratch built cluster rocket.
Your not gonna like this advice (and possibly less likely to FOLLOW IT) but buy, build, and fly a few simple rocket models. Even the little bitty ones are really a lot of fun, and you will learn from the experience. Get a new or used copy of Stine’s Handbook of Model Rocketry. It is actually an entertaining read, and trust me you will save far more money and time then it will take you to buy and read the book.
Take a hint from the experts, NASA. They didn’t launch a rocket two months after Kennedy’s speech putting Armstrong on the moon. They paced themselves with stepwise goals and got someone on the moon within the decade. Okay, yeah, the fact that they had a seemingly unlimited budget sure helped, but even WITH that, they didn’t build Rome in a day,
Your gonna sprain a lot of ankles (or worse) trying to learn to run before you can walk.
I wish you the best of luck, and remember if you aren’t having fun you aren’t doing it right!